A Florida man has been charged in an alleged backpack bomb plot in the US, the Department of Justice has said.

Harlem Suarez, also known as Almlak Benitez, 23, of Key West, was arrested on Monday (27 July) as part of an FBI sting operation.

He is charged with attempting to use a weapon of mass destruction after it was revealed he planned to carry out an attack on a public beach in Key West.

Described as a "self-professed adherent" to Islamic State, the planned attack was intended to show his support for the group, the Department of Justice said.

There is no room for failure when it comes to investigating the potential use of a weapon of mass destruction.

- FBI Special Agent George Piro

The FBI was alerted to Facebook posts including extremist rhetoric made by Suarez in April 2015, in which he expressed his support for Islamic State.

Posting a request on Facebook asking how to make a bomb, he said "send me a video or something, and what do I need to make it."

An FBI informant then made contact with Suarez, who told the informant that he wanted to carry out an attack in the United States.

He told a confidential source he planned to make a "timer bomb" and is alleged to have bought the components for the device, which was to contain galvanised nails and would have been hidden in a backpack.

He was reportedly plotting to bury the device at a public beach in Key West and then detonate it remotely by mobile phone.

Suarez was arrested on 27 July after taking possession of a device he did not realise was a fake.

"There is no room for failure when it comes to investigating the potential use of a weapon of mass destruction," said FBI Special Agent George Piro.

"The FBI and our local, state and federal partners work around the clock to prevent such catastrophic weapons from being used against our citizens."

Islamic State have been encouraging 'lone wolf attacks' in support of the terrorist group.